1. Field
Apparatuses consistent with exemplary embodiments relate to an acousto-optic device, and a light modulator, an optical scanner and a display apparatus using the acousto-optic device.
2. Description of the Related Art
The acousto-optic effect represents a changing optical property of a medium with a sound wave or an ultrasound wave. The light that enters the medium is modulated differently depending on the changed optical property of the medium and is output. For example, a refractive index of a medium may be periodically varied based on the acousto-optic effect and such a medium may function as a phase grating and thus diffract incident light.
In this case, since it is possible to change the intensity of diffracted light or a diffraction angle by adjusting a frequency and/or strength of a sound wave or an ultrasound wave that is applied to the medium, it is possible to implement a light modulator for modulating the amplitude of light, a scanner for deviating light, etc. by using the acousto-optic effect.
Acousto-optic devices that use a medium as it exists in nature generally have a limited range of acousto-optic converting efficiency. That is, in the case of a device using an existing acousto-optic medium, the device often needs a separate optical system because the range of diffraction angles of light output from the medium is not sufficiently wide, for example.
Interest in metamaterials has recently increased. Metamaterials are materials having optical properties that do not naturally exist in nature. A metamaterial may have a refractive index property that does not exist in nature, and has an artificial atomic unit that includes various patterns having a size of an order to a sub-wavelength. For an electromagnetic wave, a sound wave, or an ultrasound wave, metamaterials known which are capable of representing new phenomena, such as sub-wavelength focusing, negative refraction, extraordinary transmission, and/or invisibility cloaking. Examples of metamaterials include a photonic crystals, a plasmonic structures, etc.